The Air Force designated Convair interim interceptor the F-102A. The
production delayed, ultimate MX-1554, while retaining its original
designation, would acquire a subsequent model letter series and become the
F-102B. In 1956, after numerous engineering changes had further widened the
two interceptors' dissimilarities, the Air Force re-designated the F-102B as
the F-106.

A number of design changes were requested. The Air Force decided the F-102A
should be capable of carrying external stores (fuel
tanks, armament, and the like). Also, cockpit components of the MX-1179 ECS
(simultaneously inspected with the F-102A) had to be rearranged.

The Air Force, Convair, and Hughes agreed to equip the F-102A with an
interim fire control system, since it had become certain service test
quantities of the MX-1179 ECS would not be available prior to October 1955.
Huges E-9, a modified E-4, was selected. The MX-1179 ECS and the MX-1554
airframe had been specifically designed to complement each other, and the
MX-1179's temporary deletion from the F-102A proved to be an important
decision. In effect, it marked the defeat of the weapon system concept's first
application, for the MX-1179 never reached the F-102A. The E-9 (renamed MG-3
after a number of technical changes had substantially increased its overall
capability) was eventually replaced by the MG-10. This system (itself a former
MGR incorporating the AN/ARR-44 data link, the MG-1 automatic flight control
system, and the AN/ARC-34 miniaturized communication set) became a permanent
feature of the F-102A. Meanwhile, by almost imperceptible steps, the interim
F-102A took on greater importance, and the quantities discussed grew larger.
More emphasis on the F-102A meant less on the ultimate interceptor, leading to
an insidious program change. The realities of the development situation,
however, dictated this undesirable trend.

The F-102A's development problems first centered on its weight, which was
increasing continuously. The Westinghouse J-40 (the most powerful US turbojet
engine qualifed for production in early 1961) lacked the thrust to give the
F-102A the minimum requisite speed and altitude. Its replacement, the Pratt
and Whitney J-57P-11, officially rated as being in the 10,000 lb class and due
to enter production in February 1953, was heavier. The post mockup inspection
requirements for additional armament also generated extra weight, as did the
aircraft's new fire control system, heavier than the future MX-1179.
Meanwhile, a much more serious problem loomed.

NACA wind tunnel tests in early 1953 showed that the maximum altitude of
57,000 feet and combat radius of 350 miles (304.3 nm) predicted for the F-102A
were too optimistic. The designers of the original Convair proposal (MX-1554)
had failed to make proper allowance for a delta wing aircraft's aero-dynamic
drag. The area rule concept of aircraft design (that interference drag at
transonic speed depends almost entirely on the distribution of the aircraft's
total cross-sectional area along the direction of flight) was verified during
December 1962 by Richard T. Whitcomb in NACA's new transonic wind tunnels.

Convair drag estimates of the F-102A in its bulky amid-ship configuration
did not coincide with the data upon which they were based. The solution was to
indent the fuselage to a "coke-bottle" or "wasp waist" configuration, but
first the contractor had to be convinced that its original design was in
error. However, it was not until mid-1953 that Convair accepted the
implications of the "NACA ideal body theory" and joined in the recommendations
that the F-102A's design conform to this theory's requirements.

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The LCs, previously awarded to Convair, were superseded by a definitive
contract. This contract, still based on the Cook Craigie production plan, did
not affect the number of aircraft initially ordered. Out of the 42 aircraft
under procurement, several were earmarked for testing and two (F-102A
prototypes) were scheduled for flight in October and December 1953,
respectively. Production dates were significantly changed, however. Limited
production would not begin until April 1954--10 months later than programmed
in December 1951. Accelerated production of a combat ready, fully tested
weapon system was planned for December 1955--almost 2 years later than first
anticipated.

The first YF-102A, flown from Edwards AFB in October 1953, crashed on 2
November, but not before the aircraft's anticipated poor performance was fully
demonstrated. The flight tests, resumed several months later with the second
YF-102A (first flown on 11 January 1954), could only confirm that the F-102A
in its present configuration was drag limited to Mach .98 with a 48,000 ft
ceiling considerably below the required. The F-86D, that the F-102A was
supposed to supplant, had a service ceiling of 49,600 feet and a maximum speed
of 601.7 kn (Mach .9). It was fully operational in mid 1968, the initial
production date originally set for the F-102A.

While the MX-1179 deletion from the F-102A defeated the weapon system
concept's first application, the aircraft's unavoidable redesign made havoc of
the Cook Craigie plan for early tooling. Of the 30,000 tools already purchased
by Convair in October 1953 (when testing established unequivocally that
important changes had to be made in the plane's design), 20,000 had to be
discarded and new ones bought, a sizeable increase in production costs.
Meanwhile, the April 1954 wind tunnel and scale model tests of a remodeled
F-102A (that included cambered leading edges, reflex wing tips, rearward
relocation of wing, relocation of vertical
fin, 7 ft fuselage extension, and redesign of fuselage to incorporate the
principles of the area rule "coke-bottle" configuration) reflected continuing
deficiency in performance. Moreover; airframe and component changes had added
3,500 pounds to the aircraft's weight.

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In May 1954 the Air Force approved further redesign of the first "coke
bottle" configuration. The new drag reducing changes extended the fuselage
another four feet and added: a new canopy (lighter and providing better
visibility), new engine intake ducts, an aft fuselage fairing, and wing camber
modifications. The J-57P-23 engine (generating 16,000 pounds of thrust, or
approximately 1,200 pounds more thrust than the 11) was to replace the 11 and
the interim -41 (an 11 engine modified for new air bleed probes to eliminate
cabin fumes). A major weight reduction, likewise, was initiated.

Redesign of the F-102A, once agreed upon, was accompanied by new production
decisions. The Air Force in March 1954 gave Convair a second production
contract calling for delivery of 37 additional F-102As between February and
July 1955. A third and larger order, placed in June 1954, scheduled the
delivery of another 108 aircraft between August and December 1956.

Convair's new production contracts were soon followed by definite
qualifications. In November 1964 the Air Force issued a set of general
operational requirements that called for altitude performances up to 54,000
feet, a combat radius of 326 nautical miles, and speeds up to Mach 1.23 at
35,000 feet. The Air Force also placed an informal (but nevertheless
meaningful) hold order on the FY 1956 funds for the 108 F-102As, recently
ordered. This hold order would prevail until forthcoming flight tests of the
new F-102A proved to be satisfactory.

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A "synthetically modified" production F-102A made its initial flight and
demonstrated substantial performance improvement over the original
configuration, reaching Mach 1.22 and an altitude of 53,000 feet. This
demonstration "coke bottle" prototype (nick named the Hot Rod to distinguish
it from the two earlier YF-102As and the few initial straight fuselage
productions allocated to the testing program) was fitted with fillets designed
to the latest, light weight configuration that had been approved by the Air
Force in May 1954. It was powered by an advanced production of the improved
J-57-P-23 turbojet, due for delivery in June 1955.

Evaluation of the Hot Rod prototype's preliminary flight tests led the Air
Force to rescind in early 1955 its administrative hold order of the previous
year. Ensuing flight tests by Air Force pilots, while demonstrating that the
aircraft's stability needed improving, were also satisfactory. They ended in
June 1955, after the aircraft's initial high speed had been equaled and its
original altitude performance actually exceeded. Ten months of structural
integrity testing were initiated in July, when the Air Force concluded (after
numerous airborne firing tests) that the F-102A would be able to launch the
Falcon missile, as well as 2.75 and 2 inch rockets. A high point in the series
of armament tests was reached on 8 July, when the YF-102A fired 6 Falcons and
24 rockets in less than 10 seconds.

The first "Production Aircraft" flew on 24 June 1955. This was the first
production F-102A built to the Hot Rod, lightweight, "coke bottle"
configuration. The aircraft was accepted by the Air Force on 29 June, 5 days
after its first flight.

The F-102A first entered service with the Air Defense Command's 327th FIS
at George AFB. It became the Air Force's first delta-wing aircraft almost 3
years past the June 1963 production date in the LC of December 1951, some 7
months beyond the revised delivery schedule of 1954, and nearly 10 years after
the experimental, delta wing F-92's first flight.

One month before the F-102A entered operational service, the Air Force and
Convair decided to give the F-102A a larger fin. This new design change,
endorsed after a period of extensive testing, would alleviate the aircraft's
instability, a remaining problem particularly acute at high speeds. The change
became effective with the 26th F-102A, after Convair production schedule had
been adjusted for this purpose. Enlarged fins were retrofitted on the 25
aircraft already off the production lines.

As once planned and in order to simplify logistical support of the F-102A,
the Air Force decided in mid 1956 that (beginning with all post-December
productions) only the 2.75 inch Folding Fin Aerial Rocket would be used as
backup to the Falcon (GAR-1 and infrared -1B) guided missiles the aircraft's
primary armament. Operational F-102As and those released from production
before the decision could be implemented, would exchange their T-214 2-inch
FFARs for the standard 2.75 inch rockets. Necessary modifications were
subsequently made in the field by teams from the Air Force
San Antonio Air Materiel Area, Tex. Some 170 F-102s were modified. In the
meantime, after the first air-firing of an MB-1 rocket was accomplished from a
YF-102 in May 1956, the Air Force again considered equipping the F-102A with
Genie rockets, even though this would entail another production delay. This
project, however, was given up in early 1957.

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The Air Force gave Convair a fifth and final contract for 140 F-102As in
September 1956, 10 months after the fourth and largest (562 aircraft) F-102A
production contract had been placed.

One year after becoming operational, the F-102A still harbored a number of
deficiencies, but most defects were being corrected. By November, all F-102As
had been retrofitted with serviceable struts and the incorporation of a new
oleo strut metering pin and revision of the side brace boss bearing of the
landing gear in all future F-102A productions gave assurance that the long
standing problem of landing gear failure (susceptible of affecting also the
more advanced F-106 interceptor) was finally solved. Convair in addition had
devised a fix for speed brake failures in flight, another critical problem
which had dictated the re-inspection of speed brake in each F-102A.

While the F-102A's operational problems were being corrected, efforts to
further improve the aircraft's performance did not slacken. After a successful
prototype flight in May 1957, F-102As acquired a new wing. Referred to as the
Case XX wing and phased into production after October 1967 (beginning
approximately with the 550th F-102A), this final major structural change
raised combat ceiling to 55,000 feet (a 5,000 ft increase), boosted maximum
speed at 50,000 feet to Mach 1 (a Mach 0.06 gain), and, substantially improved
maneuverability. The F-102A's stability at low speeds, still marginal despite
the previous in-production incorporation of a larger fin, also improved
vastly.

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Modernization of the F-102A, undertaken almost concurrently with the
aircraft's final production change, lasted several years from 1957-1963. The
F-102A was still being modernized long after some of the aircraft had already
begun to leave the regular forces. This took care of the air defense needs,
increasingly provided by the Air
National Guard, and of important oversea requirements.

First involved were the addition of data links (Data links furnished the
pilot information electronically rather than by voice.) and replacement of the
MG-3 fire control system by the improved MG-10. There followed the
substitution of more sophisticated and less trouble some GAR missiles (as they
became available) and the addition of the nuclear Falcon Model Y52A. This
atomic missile, first known as the GAR-11 and subsequently re-designated the
AIM-26A, had been designed by Hughes specifically for the F-102A. In 1963,
after more than 450 aircraft had been modified and provided the necessary kits
(one kit per aircraft, at an initial cost of $10,000 per kit), half of the
F-102 interceptors (trainers included) could carry the AIM-26A. Ensuing
modifications eventually provided interchangeable utilization of AIM-26 and
AIM-4 (GAR 1 through 4 series of Falcons in post 1962 nomenclature) missiles
in the center missile bay of a number of F-102As. Under project Big Eight (and
still as part of the F-102A modernization), incorporation of an Infrared
Search and Track System into the F-102 fleet also began in 1963.